1. Field of the Invention
The present invention relates to the field of computer systems. More specifically, the present invention relates to a cost effective, high performance central processing unit (CPU) having integrated graphics capabilities.
2. Background
There are three major barriers to achieving high performance in graphics computer systems. The first barrier is in floating point processing throughput. Graphics applications typically perform large amount of figure manipulation operations such as transformations and clippings using floating point data. The second barrier is in integer or fixed point processing throughput. Graphics applications also typically perform large amount of display operations such as scan conversion and color interpolation using integer or fixed point data. The third barrier is in memory references. The above described operations typically require large amount of memory references for reading from and writing into for example the frame and Z-buffers.
Historically, the CPUs in early prior art computer systems are responsible for both graphics as well as non-graphics functions. No special hardware are provided to assist these early CPUs in performing the large amount of floating and fixed point processing, nor memory references. While the designs of these early prior art computer systems are simple, their performance are typically slow.
Some later prior art computer systems provide auxiliary display processors. The auxiliary display processors would off load these later CPUs from some of the display related operations. However, these later CPUs would still be responsible for most of the graphics processing. Typically, the bandwidth of the system buses of these later prior art computer systems are increased correspondingly to accommodate the increased amount of communications between the processors over the buses. The auxiliary display processors may even be provided with their own memory to reduce the amount of memory contentions between the processors. While generally performance will increase, however, the approach is costly and complex.
Other later prior art computer systems would provide auxiliary graphics processors with even richer graphics functions. The auxiliary graphics processors would off load the CPUs of these later prior art computer systems from most of the graphics processing. Under this approach extensive dedicated hardware as well as sophisticated software interface between the CPUs and the auxiliary graphics processors will have to be provided. While performance will increase even more, however, the approach is even more costly and more complex than the display processor approach.
In the case of microprocessors, as the technology continues to allow more and more circuitry to be packaged in a small area, it is increasingly more desirable to integrate the general purpose CPU with built-in graphics capabilities instead. Some modern prior art computer systems have begun to do that. However, the amount and nature of graphics functions integrated in these modern prior art computer systems typically are still very limited. Particular graphics functions known to have been integrated include only frame buffer checks, add with pixel merge, and add with z-buffer merge. Much of the graphics processing on these modern prior art systems remain being processed by the general purpose CPU without additional built-in graphics capabilities, or by the auxiliary display/graphics processors.
As will be disclosed, the present invention provides a cost effective, high performance CPU with integrated native graphics capabilities that advantageously overcomes much of these performance barriers and achieves the above described and other desired results.